Integral pleural drainage devices have been in common use since 1967 and have now totally replaced the three bottle system which was used prior to the development of the integral devices as disclosed in U.S. Pat. No. 3,363,626 issued Jan. 16, 1968. Such devices included a collection chamber for collecting fluid from the pleural cavity, a water seal to prevent air from entering the pleural cavity and a suction regulating system. The use of the water seal necessitates the provision of a column of water of at least 30 centimeters in height in order to prevent loss of the water seal and air entering the pleural cavity. It is, of course, quite possible that even higher degrees of negativity may exist in the pleural cavity under certain circumstances and in order to prevent loss of the water seal and to prevent air entering the pleural cavity, a float valve has been provided in the water seal chamber as shown in U.S. Pat. No. 3,683,913 issued Aug. 15, 1972.
More recently drainage devices have become more complex and include diagnostic tools which were not available to the physician previously. For example, in U.S. Pat. No. 4,605,400 issued Aug. 12, 1986 there is disclosed a bellows for indicating the respiration of a patient and in addition this patent discloses a bubble chamber for indicating the passage of air bubbles from the patient's pleural cavity to the suction source. Obviously, the addition of the diagnostic tools to the drainage device has substantially increased the cost of the disposable integral pleural drainage device.
In U.S. Pat. No. 4,883,476 issued Nov. 28, 1989, there is disclosed a drainage device in which the collection chamber which is disposable may be separated from a nondisposable section which contains all the diagnostic tools as well as the suction regulator and seal chamber. However, a need has arisen for a relatively small portable suction regulator and seal which can be used with either a separable disposable drainage device or with an autotransfusion bag.